Alpenglow lights to LED

[geoffr]

BigAI.NZ

Thanks for your comments - my light was getting very hot! (I couldn't keep my finger on the screw holding the regulator)

I have changed the Rs to reduce the power/heat. I didn't have 5.6 ohm, so used 4.7 ohm instead. I see 0.5A on high and 0.15A on low.


Here are my notes now:
• LM2940T (Creates fixed voltage so can create known current)
• 2x Cree 1304C
• 150ohm inline for Red LEDs
• 1Kohm for Low Setting on Red LEDs
• 2x 4.7 ohm for Cree (one each inline)
• 10 ohm for Low level on Cree. (this may be a bit too large)

[BigAl.NZ]

Originally Posted by geoffr

BigAI.NZ

Thanks for your comments - my light was getting very hot! (I couldn't keep my finger on the screw holding the regulator)

I have changed the Rs to reduce the power/heat. I didn't have 5.6 ohm, so used 4.7 ohm instead. I see 0.5A on high and 0.15A on low.


Here are my notes now:
• LM2940T (Creates fixed voltage so can create known current)
• 2x Cree 1304C
• 150ohm inline for Red LEDs
• 1Kohm for Low Setting on Red LEDs
• 2x 4.7 ohm for Cree (one each inline)
• 10 ohm for Low level on Cree. (this may be a bit too large)

Yeah 4.7 Ohm ought to get you in the ball park. I have settled on a 18 C/W heat sink (which hasnt arrived yet) but should keep the LM2940 under 60C even when I am operating at 14.9v when alt is charging.